After working as an attorney in patent litigation cases, Mr. Galese said he wishes more people saw the patent archives as a rich repository, flush with freely available designs. He sometimes refers to the patent office’s archives as the “original Thingiverse,” comparing it to the rapidly growing online library of design files shared by 3-D printing hobbyists today.

Others who have seen his 3-D printing files frequently ask why he keeps posting “patented” objects online, he said, not understanding that many former patents are now in the public domain.

“People don’t think people appreciate that aspect of the patent system,” he said.

Most patents issued today last 20 years, but in the past patent protections could be shorter, sometimes lasting 17 years, sometimes less. Out of the more than 8 million patents registered in the United States, only about 2 million are still in force, according to Dennis Crouch, a professor at the University of Missouri School of Law who conducted an analysis on the subject last year.